Facet joint implants and delivery tools

ABSTRACT

A spinal joint distraction system is disclosed and may include a driver assembly with a tubular shaft, a pair of implant holder arms, an implant distractor, an internal actuator, and a distractor knob, the system also including a delivery device with a tubular shaft, a receiving assembly, and a pair of forks, where the delivery device is adapted for slidable insertion of the driver assembly, the system also including an implant, a chisel, and an injector. Several embodiments of an implant are disclosed as well a method of placing an implant.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to: U.S. Provisional ApplicationNo. 61/059,723, which was filed on Jun. 6, 2008 and is entitled SpineDistraction Device; and U.S. Provisional Application No. 61/109,776,which was filed on Oct. 30, 2008 and is entitled Facet Joint Implants.The contents of all of the above-mentioned patent applications are allhereby incorporated by reference herein in their entireties.

FIELD OF THE INVENTION

The following detailed description relates to a device for distractingthe spine. More particularly the description relates to a tool fordistracting a facet joint of the spine and an implant for maintainingthe distracted position of the joint. More particularly the descriptionrelates to an implant that may be used together with a tool to distracta facet joint, the implant remaining in place separated from the tool.In some instances, the implant itself may extract the joint.

BACKGROUND

Chronic back problems cause pain and disability for a large segment ofthe population. Adverse spinal conditions may be characteristic of age.In particular, spinal stenosis (including, but not limited to, central,canal, and lateral stenosis) and facet arthropathy may increase withage. Spinal stenosis results in a reduction of foraminal area (i.e. theavailable space for the passage of nerves and blood vessels), which maycompress cervical nerve roots and cause radicular pain. Both neckextension and ipsilateral rotation, in contrast to neck flexion, mayfurther reduce the foraminal area and contribute to pain, nerve rootcompression, and neural injury.

Cervical disc herniations may be a factor in spinal stenosis and maypredominantly present upper extremity radicular symptoms. In this case,treatment may take the form of closed traction. A number of closedtraction devices are available that alleviate pain by pulling on thehead to increase foraminal height. Cervical disc herniations may also betreated with anterior and posterior surgery. Many of these surgeries areperformed through an anterior approach, which requires a spinal fusion.These surgeries may be expensive and beget additional surgeries due tochanging the biomechanics of the neck. There is a three percentincidence of re-operation after cervical spine surgery. Moreover, thesesurgeries may be highly invasive leading to long recovery times.

There is a need in the art for a device and procedure to increaseforaminal height to reduce radicular symptoms of patients suffering theeffects of spinal stenosis. There is also a need for the device to beadapted to allow for the procedure to be minimally invasive and to avoidmodifying the biomechanics of the spine.

SUMMARY OF THE INVENTION

In one embodiment, a spinal joint distraction system may include adriver assembly including a tubular shaft having a longitudinal axis anda pair of implant holder arms positioned on a distal end of the tubularshaft, where the arms are configured to hold a spinal implant. Inanother embodiment, the driver assembly may also include an implantdistractor positioned along the longitudinal axis near the distal end ofthe tubular shaft, an internal actuator positioned within the tubularshaft and adapted to advance the implant distractor, and a distractorknob adapted to control the internal actuator. In another embodiment,the system may also include a delivery device with a tubular shaft, areceiving assembly positioned on a proximal end of the tubular shaft,and a pair of forks extending from a distal end of the tubular shaft,where the may be adapted to penetrate a facet joint and the deliverydevice may be adapted to slidably receive the driver assembly. In someembodiments, the system may include an implant adapted for holding bythe implant holding arms of the driver assembly. In some otherembodiments, the system may include a chisel with a shaft portion, a tipat a distal end of the shaft, and a head at a proximal end of the shaft,where the delivery device is adapted to receive the chisel, and the headof the chisel is adapted to be tapped by a driving member to insert thetip of the chisel into a facet joint. In still other embodiments, thesystem may include an injector with a cannula with a closed distal endand two exit doors positioned on opposite sides of the distal end, aplunger with a seal positioned within the cannula, a stop disc at aproximal end of the cannula, and a handle positioned on a proximal endof the plunger, where the delivery device is further adapted to receivean injector.

In another embodiment, a spinal distraction implant may include an uppermember and a lower member, the upper and lower member being generallyrectangular and each having a distal edge, a proximal edge, and twoparallel lateral edges, the upper and lower member positioned adjacentand substantially parallel to each other and having an inner surface andan outer surface, the distal edges of the upper and lower memberconnected to each other and the proximal edges adapted to receive animplant distractor, and teeth positioned along the lateral edges of atleast one of the upper or lower member and extending outwardly. Inanother embodiment, the implant may include flanges extendingsubstantially orthogonally from a proximal end of the upper and lowermembers. In some embodiments, the flanges may include openings forreceiving anchors to anchor the implant to a lateral mass of a facetjoint.

In another embodiment, a method of distracting a facet joint of thespine may include inserting a delivery device to access the facet jointof a patient, inserting a driver assembly holding an implant into thedelivery device, and actuating the driver assembly thereby distractingthe implant.

In another embodiment, a spinal distraction implant may include an uppermember, a lower member, and a proximal member, the upper and lowermembers being generally rectangular and each having a distal edge andtwo parallel lateral edges, the upper and lower members extendinggenerally continuously into each other to form the proximal member, theupper and lower member positioned adjacent and substantially parallel toeach other and having an inner surface and an outer surface, theproximal member being generally perpendicular relative to the upper andlower members, at least one of the upper and lower members furtherincluding threaded slots adapted to receive threads of an implantdistractor and outwardly extending teeth positioned along the lateraledges of at least one of the upper or lower members. In anotherembodiment, the proximal member may include a penetration for receivingan implant distractor.

In another embodiment, a spinal distraction implant may include athreaded bolt with a proximal end terminating in a head, a proximalnon-threaded block positioned along the bolt and abutting the head ofthe bolt, a distal threaded block positioned a distance away from theproximal threaded block, and a plurality of expansion members positionedbetween the proximal and the distal threaded blocks. In one embodiment,the plurality of expansion members may be V-shaped members. In anotherembodiment, the plurality of V-shaped members may be adapted todeformably flatten out and expand laterally when compressed between thedistal and proximal blocks. In another embodiment, the plurality ofexpansion members may be planar plates with slotted holes such that whenfreely positioned on the bolt, the plates are positioned in a skewedposition relative to a longitudinal axis of the bolt. In anotherembodiment, the planar plates may be adapted to engage one another andthus position themselves perpendicular to the bolt when compressedbetween the distal and proximal blocks.

In another embodiment, a spinal distraction implant may include a pairof stacked structures separated by a sloping plane, the structureshaving an engagement surface along the plane including ratchet teeth. Inone embodiment, a first structure of the pair of stacked structuresincreases in thickness in a proximal direction and a second structure ofthe pair of stacked structures increases in thickness in a distaldirection.

In another embodiment, a spinal distraction implant may include agenerally tapered shaft in the form of a screw, the shaft defining alongitudinal axis and having a length, the shaft having threads along anouter surface for engaging articular surfaces of a facet joint. In oneembodiment, the threads may be notched along the length of the implantcreating serrations for cutting into the articular surfaces of a facetjoint. In another embodiment, the threads may include leaf springs forpreventing backing out of the implant. In another embodiment, thethreads may have a T-shaped cross-section. In another embodiment, theimplant may include a relatively broad head with a decorticating featureon a distal surface thereof. In another embodiment, the decorticatingfeature may include tabs projecting distally from the head. In anotherembodiment, the decorticating feature may include spurs. In anotherembodiment, the head may be in the form of a floating collar and be freeto pivot about the longitudinal axis of the implant in a ball and sockettype fashion. In another embodiment, the implant may include a torquelimiting mechanism. In another embodiment, the shaft may include ahollow cavity and take the form of a cone, the cone being made from arelatively malleable material, the implant further including an innercore support member for use when inserting the implant and for removalonce the implant is in place. In still another embodiment, the generallytapered shaft may be a first tapered shaft and the implant may alsoinclude a second generally tapered shaft in the form of a screw wherethe second generally tapered shaft may be positioned adjacent to thefirst generally tapered shaft and have communicative threaded serrationssuch that when one shaft is rotated, the other shaft rotates in theopposite direction. In another embodiment, the implant may include anarm type locking mechanism, the arm being biased in a distal directionsuch that when implanted the arm provides a biasing force to maintainfriction on the threads. In another embodiment, the arm may haveengaging teeth. In another embodiment, the implant may include flapsextending from the head of the shaft and including teeth for engaging alateral mass of a facet joint.

In another embodiment, a spinal distraction implant may include a plateand a orthogonally positioned bumper, the superior aspect of the bumperhaving a rounded surface for opposing the lateral mass of a superiorvertebra, the implant including an anchoring screw for securing theimplant to a lateral mass of a facet joint.

In another embodiment, a spinal distraction implant may include a wedgeinsertable between facet surfaces, the wedge having teeth on at leastone of an anterior and inferior surface thereof. In another embodiment,the implant may also include a diagonally placed anchor screw positionedthrough the implant for advancing into the surface of a facet joint.

In another embodiment, a spinal distraction implant may include ananterior hook, a posterior hook, and a bolt joining the anterior andposterior hook. In another embodiment, the anterior hook may be C-shapedwith a lip and the posterior hook may be S-shaped with a lip, theanterior hook adapted to engage the anterior aspect of the inferiorfacet and the posterior hook adapted to engage the posterior aspect ofthe posterior facet.

In another embodiment, a spinal distraction implant may include aninsert and tabs positioned to extend orthogonally from a proximal end ofthe insert. In one embodiment, the insert may be rectangular and thetabs may have holes for receiving an anchor.

In another embodiment, a spinal distraction implant may include acollapsible diamond shaped structure including two opposing threadedcorners, and two opposing non-threaded corners including pads. Theimplant may also include a bolt threaded through the threaded corners ofthe diamond shaped structure, where actuating the bolt draws thethreaded corners together and extends the non-threaded corners.

In another embodiment, a spinal distraction implant may include an uppermember, a lower member, a hinge connecting the upper member to the lowermember, and a brace member for maintaining the implant in an openposition.

In another embodiment, a spinal distraction implant may include agenerally cylindrically shaped member including at least two sectionsseparated by a slot, the sections connected together at distal ends toform a tip, the member adapted to receive a screw to cause it to expand,and the outer surface of the sections including teeth for engagingarticular surfaces of a facet joint.

In another embodiment, a method of securing a superior verterbra mayinclude applying a force to the superior vertebra to increase theforaminal area between the superior vertebra and an inferior vertebraand placing an angled screw through a superior facet, through a facetcapsule, and into an inferior facet.

In another embodiment, a spinal distraction implant may include acollapsible triangular shaped implant including a central shaft and atleast two springing leaves connected to the distal end of the shaft,extending proximally along the shaft, and biased in a direction to forman arrow shape, where the implant may be collapsed within a tube anddelivered to a site where the tube is removed and the implant is allowedto expand.

In another embodiment, a spinal distraction implant may include a facetspacer plate and screw, wherein the screw may be inserted diagonallythrough a facet surface to engage the facet spacer plate thereby forcingseparation of a facet joint. In another embodiment, the spacer may havea C-shape and the screw may pass through the spacer plate prior toentering the spinal structure.

In another embodiment, a spinal distraction implant may include a firstbracket, second bracket, and a bolt extending between the brackets,where the brackets are adapted to separate when the bolt is turned. Inanother embodiment, the first and second brackets may be adapted to beattached to a lateral mass of a facet joint. In yet another embodiment,the first and second brackets may include a leg adapted to be insertedinto a facet joint.

In another embodiment, a spinal distraction implant may include atriangular shaped wedge, an anchor screw positioned diagonally throughthe wedge, and a malleable flap extending from the wedge including teethfor engaging a lateral mass of a facet joint.

In another embodiment, a spinal distraction implant may include ananchoring plug, an expandable plate, and two external plates, wheresecuring the external plates to a lateral mass of a facet joint andinserting the anchoring plug causes the facet joint to separate.

In another embodiment, a spinal distraction implant may include adelivery system and at least two nitinol hooks, where the hooks may beflattened and inserted with the delivery system and once in place may beallowed to assume their pre-flattened shape.

In another embodiment, a spinal distraction implant may include a hollowscrew sleeve having barbs adapted to be ejected from a retractedposition and a wedge adapted to be inserted in the hollow screw sleeveto eject the barbs.

In another embodiment, a spinal distraction implant may include acollapsible nut positioned over a bolt, the bolt defining a longitudinalaxis, where advancing the bolt may cause the nut to collapse along thelongitudinal axis in an accordion shape, thereby expanding laterally.

In another embodiment, a spinal distraction implant may include acollapsible plate positioned over a bolt, the bolt defining alongitudinal axis, where advancing the bolt causes the plate to collapsealong the longitudinal axis in an accordion shape, thereby expandinglaterally.

In another embodiment, a spinal distraction implant may include a wiresurrounding a block in a helical fashion, the wire adapted to contractand expand laterally when pulled taught or released respectively.

In another embodiment, a spinal distraction implant may include an outerhousing and an internal spring, where the housing may be biased to be ina laterally broad position when the spring is in a neutral position.

In another embodiment, a spinal distraction implant may include a pairof stacked structures separated by a sloping plane and a fastenerpositioned at an angle through the pair of structures thereby preventingrelative movement along the plane.

In another embodiment, a spinal distraction implant may include acollapsible cylinder with side cutouts, the cylinder made from aresilient elastic material.

In another embodiment, a spinal distraction implant may include a distaltip of a delivery tool, where the tip is adapted to distract a facetjoint and detach from the delivery tool.

In another embodiment, a spinal distraction implant may include ahousing, a central gear rotatably positioned within the housing, and twoplates slidably positioned in the housing and positioned opposite oneanother adjacent to the central gear and including teeth for engagingthe gear, where rotating the gear slidably extends the plates beyond anouter surface of the housing in opposite directions.

In another embodiment, a spinal distraction implant may include atriangularly bent plate with a first and second bracket on each side,the first bracket adapted to receive an anchor screw and the secondbracket including teeth for biting into a lateral mass of a facet joint.

In another embodiment, a spinal distraction implant may include arotatable cone with a longitudinal axis including a shoulder with aledge defining a cam surface and an anchor screw, where the shoulder isadapted to be inserted into a facet joint and the implant rotated tocause a superior facet to ride upward along the cam surface and distractthe joint, wherein the screw may be advanced to secure the implant.

In another embodiment, a spinal distraction implant may include ahousing with penetrations for ejection of spikes, internal spikespositioned with the housing and in alignment with the penetrations, andan internal wire routed through the spike positions, where pulling thewire taught forces the spikes from the housing to engage articularsurfaces of a facet joint.

In another embodiment, a spinal distraction implant may include ahousing, a cavity within the housing, penetrations on lateral surfacesof the housing extending from the cavity through the wall of thehousing, spikes positioned to be ejected through the penetrations, thespikes having a beveled inner surface, and a piston having a torpedoshaped distal end positioned within the cavity, where advancing thepiston engages the torpedo shaped distal end with the beveled innersurface of the spikes causing them to eject through the penetrations andengage articular surfaces of a facet joint.

In another embodiment, a spinal distraction implant may include twoparallel equal length side bars and at least two struts pivotablypositioned between the side bars at each end, the struts having texturedsurfaces on each end thereof, where the struts may be pivoted to lie inplane with and parallel to the side bars and once in position in a facetjoint, may be pivoted substantially perpendicular to the side bars todistract the facet joint.

Further aspects of the invention will be brought out in the followingportions of the specification, wherein the detailed description is forthe purpose of fully disclosing preferred embodiments of the inventionwithout placing limitations thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a delivery device and chisel positionedrelative to a facet joint of a spine, according to certain embodiments.

FIG. 1A is a perspective view of a chisel according to certainembodiments.

FIG. 2 is a perspective view of a distal end of a delivery device,according to certain embodiments.

FIG. 3 is a perspective view of a distal end of a delivery device withan advanced chisel, according to certain embodiments

FIG. 4 is a perspective view of a distal end of a delivery device withan advanced internal decorticator, according to certain embodiments.

FIG. 5 is a perspective view of a delivery device and chisel positionedrelative to a facet joint of a spine with a driving member positionedproximally to the chisel head, according to certain embodiments.

FIG. 6 is a perspective view of a delivery device with an exteriordecorticator in an advanced position, according to certain embodiments.

FIG. 6A-6C are perspective views of a delivery device and an internaldecorticator, according to certain embodiments.

FIG. 7 is a perspective view of a delivery device with an exteriordecorticator being retracted, according to certain embodiments.

FIG. 8 is a perspective view of a delivery device with a driver assemblyand implant poised for insertion into the delivery device, according tocertain embodiments.

FIG. 9 is a close-up view of a distal end of a driver assembly and adelivery device, according to certain embodiments.

FIG. 10 is close-up view of a distal end of a driver assembly, accordingto certain embodiments.

FIG. 11 is a perspective view of an implant and a distal end of a driverassembly, according to certain embodiments.

FIG. 12 is a perspective view of distal end of a driver assembly holdingan implant, according to certain embodiments.

FIG. 13 is a perspective view of a distal end of a driver assemblypositioned within a delivery device, according to certain embodiments.

FIG. 14 is a perspective view of an implant distractor, according tocertain embodiments.

FIG. 15 is a perspective view of a distal end of a driver assemblypositioned within a delivery device, according to certain embodiments.

FIG. 16 is a perspective view of an implant according to certainembodiments.

FIG. 16A is a perspective view of an implant showing a guide feature,according to certain embodiments.

FIG. 16B is a perspective view of an implant showing a guide feature,according to certain embodiments.

FIG. 17 is a side view of an implant according to certain embodiments.

FIG. 18 is a top view of an implant according to certain embodiments.

FIG. 18A is a top view of an implant showing the guide feature of FIG.16A, according to certain embodiments.

FIG. 18B is a top view of an implant showing the guide feature of FIG.16B, according to certain embodiments.

FIG. 19 is a proximal end view of an implant according to certainembodiments.

FIG. 20 is a side view of an implant according to certain embodiments.

FIG. 21 is side view of a U-member according to certain embodiments.

FIG. 22 is a perspective view of a U-member according to certainembodiments.

FIG. 23 is a perspective view of an implant according to certainembodiments.

FIG. 23A is a perspective view of an implant according to certainembodiments.

FIG. 24 is a top view of an implant according to certain embodiments.

FIG. 24A is a side view of the implant shown in FIG. 23A, according tocertain embodiments.

FIG. 25 is perspective view of a deliver device with a driver assemblyinserted and advance, according to certain embodiments.

FIG. 26 is perspective view showing the removal of the driver assemblyfrom the delivery device having left the implant behind, according tocertain embodiments.

FIG. 27 is a perspective view of an injector, according to certainembodiments.

FIG. 28 is a perspective view of a delivery device with an advancedinjector inserted and ejecting a material, according to certainembodiments.

FIG. 29 is a perspective view of an implant in a collapsed positionaccording to certain embodiments.

FIG. 30 is a perspective view of an expanded implant according tocertain embodiments.

FIG. 31 is a perspective view of an implant in a collapsed positionaccording to certain embodiments.

FIG. 32 is a perspective view of an expanded implant according tocertain embodiments.

FIG. 33 is a perspective view of an implant in a collapsed positionaccording to certain embodiments.

FIG. 34 is a perspective view of an expanded implant according tocertain embodiments.

FIG. 35 is a perspective view of an implant in a collapsed positionaccording to certain embodiments.

FIG. 36 is a perspective view of an expanded implant according tocertain embodiments.

FIGS. 37A-D include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 38A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 39A-D include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 40A-C include side views of an implant, according to certainembodiments.

FIGS. 41A-D include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 42A-F include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 43A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 44A-D include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 45A-D include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 46A-D include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 47A-B include side views of an implant, according to certainembodiments.

FIGS. 48A-C include side and end views of an implant, according tocertain embodiments.

FIGS. 49A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 50A-B include side views of an implant, according to certainembodiments.

FIGS. 51A-B include side views of an implant, according to certainembodiments.

FIGS. 52A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 53A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 54A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 55A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 56A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 57A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 58A-B include side views of an implant, according to certainembodiments.

FIGS. 59A-B include side views of an implant, according to certainembodiments.

FIGS. 60A-B include side views of an implant, according to certainembodiments.

FIGS. 61A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 62A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 63A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 64A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 65A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 66A-C include side views of an implant, according to certainembodiments.

FIGS. 67A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 68A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 69A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 70A-C include side views of an implant, according to certainembodiments.

FIGS. 71A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 72A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 73A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 74A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 75A-B include side views of an implant, according to certainembodiments.

FIGS. 76A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 77A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 78A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 79A-C include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 80A-D include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 81A-C include side views of an implant, according to certainembodiments.

FIGS. 82A-F include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 83A-B include side and perspective views of an implant, accordingto certain embodiments.

FIGS. 84A-B include perspective views of an implant, according tocertain embodiments.

FIG. 85 is an exploded perspective view of a kit, according to certainembodiments.

FIG. 86 is an assembled perspective view of a kit, according to certainembodiments.

FIGS. 87 and 88 are perspective views of a chisel portion of the kitshown in FIGS. 85 and 86.

FIGS. 89 and 90 are perspective views of a delivery device portion ofthe kit shown in FIGS. 85 and 86.

FIG. 91 is a perspective view of part of a driver assembly portion ofthe kit shown in FIGS. 85 and 86.

FIGS. 92 and 93 are perspective views of a part of a driver assemblyportion of the kit shown in FIGS. 85 and 86.

DETAILED DESCRIPTION OF THE INVENTION

The following description generally relates to devices and methods fortreating spinal stenosis. Spinal stenosis reflects a narrowing of one ormore areas of the spine often in the upper or lower back. This narrowingcan put pressure on the spinal cord or on the nerves that branch outfrom the compressed areas. Individual vertebrae of the spine arepositioned relative to each other and their separation is maintained bydiscs separating main vertebral bodies and by capsules positioned withinfacet joints. The discs and capsules are separated from the bone oftheir respective joints by cartilage. Spinal stenosis is oftenindicative of degeneration of a disc, a capsule, or the cartilage in ajoint, which leads to a compression of the joints and the narrowingmentioned.

As such, the following detailed description includes discussion of adevice for distracting a facet joint of the spine to remedy thiscondition. The device may include a tool and an implant for distractingand maintaining the distracted position of the joint. Severalembodiments of an implant are described in addition to severalembodiments of a tool. In addition, several embodiments are describedwhere the implant and the tool work together to distract the facet jointand thereafter leave the implant behind to maintain the distraction ofthe joint. In short, the device may be adapted to access a facet jointby inserting a delivery tool and an implant, forcibly separate theassociated articular surfaces with the tool, the implant, or both, andleave the implant in place to maintain the separation of the articularsurfaces. This approach may allow for maintaining the distraction of thejoint, thereby relieving symptoms associated with spinal stenosis.

The present application hereby incorporates the following U.S. patentapplications by reference herein in their entireties: U.S. patentapplication Ser. No. 11/618,619, which was filed on Dec. 29, 2006 and isentitled Cervical Distraction Device; U.S. Provisional PatentApplication No. 61/020,082, which was filed on Jan. 9, 2008 and isentitled Methods and Apparatus for Accessing and Treating the FacetJoint; U.S. Provisional Application No. 61/059,723, which was filed onJun. 6, 2008 and is entitled Spine Distraction Device; U.S. ProvisionalApplication No. 61/097,103, which was filed on Sep. 15, 2008 and isentitled Cervical Distraction/Implant Delivery Device; and U.S.Provisional Application No. 61/109,776, which was filed on Oct. 30, 2008and is entitled Facet Joint Implants.

Referring now to FIGS. 1-28, a first embodiment of a tool and an implantis shown. FIG. 1 shows the tool 100 in position posterior to the spine102. The tool 100 includes a delivery device 104, a decorticator 106,and a chisel 108.

The delivery device 104 may include a receiving assembly 110 at aproximal end, anchoring forks 112 at a distal end, and a generallytubular shaft 114 defining a longitudinal axis and extending between thereceiving assembly 110 and the anchoring forks 112. The tubular shaft114 may have an annular shaped cross-section with an inner radius and anouter radius, where the difference between the two radii defines athickness of the tubular shaft 114.

The receiving assembly 110 of the delivery device 104 may have agenerally conical outer surface defining a generally hollow volume orsolid mass. The conical outer surface may have a longitudinal axis thatcoincides with that of the tubular shaft 114. The conical outer surfacemay be defined by a first radius at a proximal end and a second radiusat a distal end. Where the tubular shaft 114 and the receiving assembly110 are manufactured as one piece, the second radius may match the outerradius of the tubular shaft. Alternatively, the distal end of thereceiving assembly 110 may be adapted for a press fit over the proximalend of the tubular shaft 114. The receiving assembly 110 may alsoinclude a longitudinally extending bore 116 having an inner radiusmatching that of the tubular shaft 114 or may have a conically shapedinner surface leading to the tubular shaft 114. The receiving assembly110 may also include a relatively thin annular ring 118 offset from itsdistal end by two relatively thin extension elements 120. The spacebetween the proximal end of the conical portion of the receivingassembly 110 and the distal end of the annular ring 118 may define anaccess opening 122.

In another embodiment as shown in FIGS. 6A-6C, a receiving assembly 111may not include the annular ring 118 and the extension elements 120, butmay remain generally conical and may include the longitudinallyextending bore 116. In addition, near the proximal end of the receivingassembly 111, seating recesses 119 may be included. These recesses 119may be positioned on opposing sides of the bore 116 and may recess intothe proximal end of the receiving assembly 111 and the inner surface ofthe bore 116. These recesses may function to receive positionallymatched protrusions from any one or all of the devices being insertedinto the deliver device. As such, the recesses 119, may allow fororienting the devices properly relative to the forks 112 positioned inthe facet joint. It is noted that any number of recesses may be providedand that any orientation may be used, either symmetrical ornon-symmetrical, such that one or several orientations may becontrolled. That is, an asymmetrical arrangement may allow for only oneproper insertion position as opposed to the symmetrical orientationshown, which may allow for two proper insertion positions.

As shown in more detail in FIG. 2, the delivery device 104 may includetwo anchoring forks 112 formed by coping two opposing portions of thedistal end of the tubular shaft 114. The forks 112 may have a generallyV-shaped tip 124 at their distal end and may have a generallyrectangular cross-section extending from the V-shaped tip 124 to theproximal end of the forks 112. The rectangular cross-section may have aninside face and an outside face where the inside face faces thelongitudinal axis of the delivery device 104. The rectangularcross-section may also have opposing surfaces connecting the inside faceto the outside face and completing the rectangular cross-section. At theproximal end of the forks 112, as suggested by the coping mentionedabove, the cross-section may gradually change from rectangular to ashape matching that of half of the annular shape of the tubular shaftportion. The forks 112 may also include serrations or teeth along theopposing surfaces to assist with anchoring the delivery device 104.

Referring again to FIG. 1, the chisel 108 may have a generallycylindrical cross-section forming a shaft 128. The shaft 128 may have aradius substantially equal to the inner radius of the tubular shaft 114portion of the delivery device 104 allowing for slidable insertion ofthe chisel 108 within the delivery device 104. The chisel 108 mayinclude a basic single or doubly chamfered tip 130 at a distal end ormay have a coped distal end. The chisel 108 may also include a head 132at a proximal end. The head 132 may be a generally solid material andmay have a generally flat distal face and a spherically shaped proximalface. The shaft 128 and tip 130 portion of the chisel 108, measured fromthe distal face of the head 132 to the distal end of the chamfered tip130, may have a length substantially equal to the distance from aproximal face of the annular ring 118 of the delivery device 104 to thedistal tip of the delivery device 104.

In another embodiment, the chisel 108 may include a longitudinal lumen131 as shown in FIG. 1A. While not shown, this embodiment may alsoinclude the head 132 shown in FIG. 1 and the lumen 131 may extend therethrough. The lumen 131 in the chisel 108 may be used for advancing ascope along with the chisel 108 to properly place the chisel 108 and thedelivery device 104. The lumen 131 may also be used to provide suctionor fluid flushing to the surgical site to remove or flush debris createdby inserting the serrated forks 112 of the delivery device 104 and thetip 130 of the chisel 108.

As shown in FIG. 3, the tip 130 of the chisel 108 may have a copedshaped similar to that of the forks 112 of delivery device 104. In thiscondition, the tip 130 may include a generally V-shaped distal endmatching that of the forks 112. The tip 130 may have a widthsubstantially equal to twice the inner radius of the tubular shaft 114of the delivery device 104 such that the tip 130 extends between the twoinside faces of the forks 112.

Referring again to FIG. 1, the decorticator 106 may have a tubular shaft134 portion, an abrasive distal end 136, and a handle 138 at a proximalend. The tubular shaft 134 may have an inner radius substantially equalto the outer radius of the tubular shaft 114 of the delivery device 104and may allow for sliding movement of the decorticator 106 along thelength of the delivery device 104 and rotationally around the deliverydevice 104. The abrasive distal end 136 may include serrated teeth asshown, or may include a more flat annular surface with a gritty surface.The handle 138 may have a generally cylindrical portion with randomly orpatterned raised portions or recesses adapted to assist gripping thehandle. The proximal and distal ends of the handle 138 may be generallyspherical. It is noted that the decorticator 106 may alternatively beseparate from the delivery device 104 and may be slidably insertedwithin the delivery device 104 as shown in FIG. 4. In this embodiment,the decorticator 106 may be inserted, advanced to the implantation site,and rotated similar to the decorticator 106 described above to roughenthe bone surface.

In still another embodiment, a decorticator 106 may take the form of arelatively sharp pick, as shown in FIG. 6A-6C. As shown in FIG. 6A, thedecorticator 106 may include a control handle 139 for advancing andpivoting the device. The control handle 139 may be connected to atubular shaft 135, which may be connected to a sharp flexible tip 137.As shown, the tip 137 may be relatively thin and may have a neutralposition relative to the longitudinal axis of the delivery device 104 soas to position the tip 137 within the boundary defined by the innersurface of the delivery device 104. As such, when inserted in thedelivery device 104, the tip 137 may slide readily through the deliverydevice 104. When the decorticator 106 is advanced to the distal end ofthe delivery device 104, the tip 137 may be rotated and maneuvered todecorticate the surface of the lateral mass. It is noted that the shaft135 may be relatively narrow when compared to the inner bore of thedelivery device 104 to facilitate better maneuverability of the tip ofthe decorticator as it extends out the end of the deliver device. Thedecorticator may be used as shown in FIGS. 6B and 6C to rotationallyscrape or longitudinally penetrate the lateral mass of a facet joint. Adriving member may be used to assist the decorticating process.

Referring now to FIG. 5, the tool 100 is shown with the chisel 108 fullyinserted into the delivery device 104 such that the distal face of thehead 132 of the chisel 108 is in abutting relationship with the annularring 118 of the receiving assembly 110 on the delivery device 104. Thedistal tip 130 of the chisel 108 thus extends to the distal end of thedelivery device 104. A hammer 140 is shown for use in tapping theproximal end of the chisel 108 and thus advancing the forks 112 of thedelivery device 104 and the tip 130 of the chisel 108 into the facetjoint. As the chisel 108 and the delivery device 104 are advanced intothe joint, the forks 112 of the delivery device may channel into thefact surface and displace or remove tissue. In some embodiments, thismay be removed by a suction lumen in the chisel. Once the chisel 108 anddelivery device 104 are tapped into place, the chisel 108 may be removedand the serrations on the opposing surfaces of the forks 112 may aid inanchoring the delivery device 104 in the joint and preventingdislodgement.

FIG. 6 shows the decorticator 106 in an advanced position along thelength of the delivery device 104 such that the distal end is in contactwith the bone surfaces surrounding the facet joint. The handle 138 isbeing used to rotate the decorticator 106 around the perimeter of thedelivery device 104 to roughen the associated bone surfaces.Alternatively, either of the internal decorticators shown in FIGS. 4 or6A-6C may be used.

FIG. 7 shows the decorticator 106 retracted and also shows the resultingroughened bone surfaces.

Referring now to FIG. 8, the tool 100, including the delivery device 104and retracted decorticator 106, is shown lodged in a facet joint. Alsoshown is a driver assembly 142 portion of the tool 100. The driverassembly 142 includes a distractor knob 144, an implant shaft 146,implant holding arms 148, an implant distractor 150, and an internalactuator 152(not shown). The driver assembly 142 shown is holding animplant 154 and is poised for insertion into the delivery device 104.

Referring now to FIGS. 9-15 several views of the driver assembly 142 areshown. In FIG. 9, a portion of the delivery device 104 is shown forreceiving the driver assembly 142. The distal end of the driver assembly142 is also shown. FIG. 10 shows a close-up view of the distal end ofthe driver assembly 142 where the implant 154, the implant distractor150 and the internal actuator 152 are not shown. As shown, the implantshaft 146 of the driver assembly 142 defines a longitudinal axis thereofand has a generally annular cross-section with an inner radius and anouter radius where the difference between the two radii defines the wallthickness of the shaft 146. The outer radius of the implant shaft 146 issubstantially equal to the inner radius of the tubular shaft 114 of thedelivery device 104. The implant shaft 146 also includes a keywayfeature 156 for preventing relative rotation between the tubular shaft114 of the delivery device 104 and the implant shaft 146 of the driverassembly 142 when inserted. As shown, the keyway feature 156 may includea pair of tabs on opposing sides of the implant shaft 146 for engagingwith a corresponding longitudinal slot in the inner surface of thetubular shaft 114 of the delivery device 104. In another embodiment,this keyway feature 156 may be in the form of a longitudinal slot in theouter surface of the implant shaft 146 of the driver assembly 142, asshown in FIG. 11, which may receive an internal ridge, tab, or otherprotrusion from the inner surface of the tubular shaft 114 of thedelivery device 104.

With continued reference to FIG. 10, two arms 148 are shown extendingfrom the distal end of the implant shaft 146. The arms 148 may be formedby coping opposing surfaces of the implant shaft 146. As shown, the arms148 have a generally rectangular cross-section with an inside facefacing the longitudinal axis of the implant shaft 146 and an oppositeoutside face. The inside and outside faces of the cross-section areconnected by two opposing faces. The arms 148 may include an engagementfeature 158 at a distal end for engaging an implant 154. As shown, theengagement feature 158 may include a generally rectangular elementpositioned orthogonal to the arms 148 and flush with the outside face ofthe arms. As shown in FIG. 9, the implant 154 may slide over the distalend of the arms 148 and may include a receiving feature 160 forreceiving the engagement feature 158 of each of the arms 148.

Referring now to FIG. 11, another embodiment of the arms 148 is shown inrelation to an implant 154. In this embodiment, the arms 148 may stillbe formed by coping opposing surfaces of the implant shaft 146. In thisembodiment, the outside face of the arm 148 may be a continuation of theoutside surface of the implant shaft 146. However, the inside face ofthe arm 148 is more detailed than that of the embodiment shown in FIG.10. That is, as shown in FIG. 11, the inside surface may include alongitudinal ridge 162 extending the length of the arm 148. The arm 148may also include a bull nose engagement feature 158 extending transverseto the longitudinal axis of the implant shaft 146 along the inside faceof the arm 148. As shown in FIG. 12, where the arms 148 are engaged withand holding the implant 154, the longitudinal ridges 162 of each arm 148are positioned between upper and lower planar members of the implant 154and the bull nose engagement features 158 are positioned in the U-shapedreceiving feature slots 160 on the lateral edges of the implant 154.

The implant distractor 150 is shown in FIG. 9 and a close-up view isshown in FIG. 14. The implant distractor 150 may be a generally narrowconical element tapered to a point at a distal end. At a proximal end,the implant distractor 150 is shown to include an extruded hexagon shape164. In the present embodiment, the outer surface of the implantdistractor 150 includes a continuous coil-shaped thread feature 166. Theimplant distractor 150 is shown positioned proximal to the implant 154and engaged by the internal actuator 152. Those of skill in the art willunderstand and appreciate that the implant distractor 150 may take on avariety of shapes and sizes other than that shown in the presentembodiment. For example, the implant distractor 150 may be a triangularshaped wedge, a generally conical shape without threads, or other shapeadapted to cause separation and distraction of a facet joint.

Referring again to FIG. 9, the internal actuator 152 is visibleextending from the distal end of the implant shaft 146. The internalactuator 152 generally includes a longitudinal shaft positioned withinthe driver assembly 142. The internal actuator 152 may have a radiussubstantially equal to the inner radius of the driver assembly 142 andmay be adapted for slidable longitudinal and rotational movementrelative to the driver assembly 142. The internal actuator 152 may bemoved relative to the implant shaft 146 longitudinally, rotationally, orboth via the distractor knob 144 and may cause a corresponding motion ofthe implant distractor 150. As such, the internal actuator 152 mayadvance the implant distractor 150 into the implant 154 thus expandingthe implant 154 in the joint causing distraction of the joint. Thedistal end of the internal actuator 152 may include a hex driver typetip as most clearly shown in FIG. 15 for engaging the extruded hexagonalshaped proximal end of the implant distractor 150. Those skilled in theart will understand and appreciate that several driving engagements areknown in the art including flat screwdriver types, phillips head types,square drive, etc. and that these are within the scope of the invention.

In one embodiment, when the driver assembly 142 is inserted, it maycarry the internal actuator 152, the implant distractor 150, as well asthe implant 154 with it. However, to properly position the driverassembly 142 and the implant 154, some force may be required via amallet or other member driving member. In this embodiment, the internalactuator 152 may be slightly isolated from the driver assembly 142, soas to avoid advancing the internal actuator 152, and thus the implantdistractor 150, when forcing the driver assembly 142 into the joint.This isolation may help to avoid inadvertently advancing the internalactuator 152 and the implant distractor 150, thus avoiding inadvertentdistration prior to proper placement. The isolation of the internalactuator 152 from the driver assembly may take the form of a looselyfitting threaded engagement between the driver assembly 142 and theinternal actuator 152. Alternatively, this isolation may be in the formof a clip between the two features.

For a detailed discussion of an implant 154 according to certainembodiments, reference is now made to FIGS. 16-24.

As can be understood from FIGS. 16 and 17, the implant 154 may includeupper 168 and lower 170 members. The members 168, 170 may be generallyplanar and may also be generally rectangular. As most clearly shown inFIG. 18, each of the upper 168 and lower 170 members may include aproximal edge 172, a distal edge 174, and a pair of parallel lateraledges 176 extending longitudinally between the distal edges 174 and theproximal edges 172. The distal 174 and proximal edges 172 may begenerally square edges, while the lateral edges 176 may be defined by aradiused curve. As shown in cross-section in FIG. 19, the inner surface178 of the upper 168 and lower 170 member may be generally flat as itapproaches the lateral edge 176. Gradually, the inner surface 178departs from generally flat and follows a radiused curve until itintersects with the outer surface 180. The members 168, 170 may bejoined at their respective distal edges 174 by a U-member 182 to form aleading end. Alternatively, as shown in FIGS. 23 and 24, the leading endmay be formed via a weld (not shown) that couples the distal edges 174of the planar members 168, 170 together. In yet another embodiment, theupper 168 and lower 170 members may be formed from a single plate bentto create the implant as shown in FIGS. 23A and 24A. In any or all ofthese embodiments, the planar members 168, 170 may be biased by theleading end to be generally parallel to each other, the inner faces 178of the planar members 168, 170 facing each other in an opposed fashionand abutting or nearly abutting each other. A guide feature 184 may beincluded on each of the upper 168 and lower 170 members as well as teeth186 projecting outwardly from the outer faces 180 of the members 168,170. The receiving features 160 mentioned above with respect to FIGS. 11and 12 may also be included. Threaded slots 188 may also be included ineach planar member 168, 170 for receiving the coil-shaped thread feature166 on the implant distractor 150.

With continued reference to FIGS. 16 and 17, the guide feature 184 maytake the form of a half-conical feature and may be positioned at or nearthe proximal edge 172 of each of the upper 168 and lower 170 members.The half-conical feature may begin at the proximal edge 172 with thewidest radius of the half-conical feature and may taper to a zero orapproximately zero radius as the half-conical feature extends in thedirection of the distal edge 174. Where the upper 168 and lower 170members are in parallel position, the half conical features may opposeone another and function to receive and guide an advancing implantdistractor 150. As such, like the upper 168 and lower 170 membersdescribed above, the half-conical features may also include threadedslots 188 for receiving the coil-shaped thread feature 166 on theimplant distractor 150. In other embodiments, the half-conical featuremay not actually be a full half cone. Instead, the proximal end of thefeature may be a segment of a circle and the feature may be relativelysubtle in the form of a cone segment. In another embodiment the guidefeature 184 may include a V-shaped notch or a rectangular notch in theproximal end of the upper 168 and lower 170 members as shown in FIGS.16A and 18A and FIGS. 16B and 18B respectively. Those skilled in the artwill understand and appreciate that other shaped notches or elements maybe positioned on proximal end of the upper 168 and lower 170 members toguide the implant distractor 150, and these elements are within thescope of the present disclosure.

As shown, the upper 168 and lower 170 members may also each includeteeth 186 projecting outwardly (e.g. a direction opposite the positionof the other upper or lower member) from the outer surfaces 180 of theupper 168 and lower 170 members. As shown in FIG. 17, the teeth 186 maybe equally spaced along each lateral edge 176 and may have a linearlysloped distal face 190 and a proximal face 192 oriented orthogonally toits respective upper 168 or lower 170 member. The distal face 190 andproximal face 192 may intersect to form a point 194. The teeth 186 mayalso be bounded by opposing inside 196 and outside 198 lateral facesseparated by a thickness approximately equal to the thickness of theupper 168 and lower 170 members. As shown in FIG. 19, the outside face198 of the teeth 186 follows an extension of the radiused curve formedby the inner surface 178 of the upper 168 or lower 170 member at thelateral edge 176, this curve being referred to as a first radiusedcurve. Additionally, the inside face 196 of the teeth 186 follows asecond radiused curve offset from the first radiused curve, such thatthe teeth 186 have a generally constant thickness from the locationwhere they depart from the outer surface 180 of the upper 168 or lower170 member to the point 194. The radiused shape of the teeth 186 allowsthe implant 154 to slidably engage the inside of the delivery device 104when it is advanced toward the implantation site. Those skilled in theart will understand and appreciate that one, as opposed to both, of theupper 168 and lower 170 members may include teeth 186 to facilitatefreedom of motion of the facet joint once the implant 154 is in place.

As shown in FIGS. 16 and 17, where a U-member 182 is used to connect theupper 168 and lower 170 members, the U-member 182 may overlap the upper168 and lower 170 members. Alternatively, as shown in FIG. 20, theU-member 182 may attach to the distal ends 174 of the upper 168 andlower 170 members via a butt joint. In either case, the U-member 182 maybe fastened via welding, fusing, or other techniques known in the art.As shown in FIGS. 21 and 22, the U-member 182 may be a relatively thin,generally rectangular piece of material formed into the shape of theletter ‘U’. The rectangular piece of material may have a length definedby the amount of overlap of the upper member 168 and the lower member170 in addition to the length associated with hairpin or U portion ofthe member 182. The width of the rectangular plate may be substantiallyequal to the distance between the teeth 186 of the upper 168 and lower170 members. The U-member 182 may be adapted to provide the parallelbiased position mentioned and yet allow distraction of the upper 168 andlower 170 member when a separation force is applied, the proximal edge172 of the upper 168 and lower 170 member distracting more than thedistal edge 174.

As shown in FIGS. 23 and 24, where the distal edges 174 of the upper 168and lower 170 member are joined via welding, the distal edges 174 mayinclude a notch to facilitate more weld length and to cause flexure tooccur in the upper 168 and lower 170 members rather than in the welditself. Also shown in FIGS. 23 and 24 are the U-shaped receiving featureslots 160 for receiving the bull nosed engagement features 158 of thearms 148 of the driver assembly 142. As shown most clearly in FIG. 24,the U-shaped receiving feature slots 160 are positioned between theequally spaced teeth 186 and extend into the lateral edges 176 of theupper 168 and lower 170 member just beyond the inside edge of where theteeth 186 begin extending from the outer surfaces 180.

The receiving feature 160 may take several forms including a rectangularnotch in the lateral edge 176 of the upper 168 and lower 170 member or aU-shaped notch. The receiving feature 160 may be adapted to receive anengagement feature 158 positioned on the arm 148 of the driver assembly142. The receiving feature 160 may be any shaped recess and may beadapted to be engaged by the engagement feature 158 so as to prevent orlimit relative longitudinal motion between the arms 148 and the implant154, when the implant 154 is in the neutral position. However, when inan expanded or distracted position, the receiving features 160 may besuch that they are lifted free of the engagement feature 158 of the arms148, thus allowing relative longitudinal motion between the driverassembly 142 and the implant 154.

The driver assembly 142 and implant 154 described with respect to FIGS.8-24, may be used to distract a facet joint. With the delivery device104 positioned as shown and described with respect to FIG. 7, theimplant 154 may be positioned to be held by the arms 148 of the driverassembly 142. The driver assembly 142 and implant 154 may then beinserted into the delivery device 104 and slidably advanced such thatthe implant 154 is positioned between the forks 112 of the deliverydevice 104 and within the facet joint. The advanced position of thedriver assembly 142 and implant 154 within the delivery device 104 maybe most clearly seen in FIG. 13. The proximal end of the driver assembly142 may be tapped on to fully advance the driver assembly 142 andproperly position the implant 154. The implant shaft 146 of the driverassembly 142 may be prevented from rotating by the keyway feature 156securing it against relative rotation with respect to the deliverydevice 104. As such, once positioned, the distractor knob 144 of thedriver assembly 142 may be turned, as shown in FIG. 25, therebyadvancing the internal actuator 152 and further advancing the implantdistractor 150. In the embodiment described, the coil-shaped threadfeature 166 on the implant distractor 150 may engage the threaded slots188 of the half-conical features 184 of the upper 168 and lower 170members of the implant 154. As such, the implant distractor 150 may beguided and remain in position to further engage the threaded slots 188on the upper 168 and lower 170 members. As the implant distractor 150continues to advance, those of skill in the art will understand andappreciate that its tapered shape advancing between the upper 168 andlower 170 members will force the upper 168 and lower 170 members of theimplant 154 apart causing them to pivot about a point defined by theattachment to each other at their distal ends 174. As the implant 154continues to be distracted, the upper 168 and lower 170 members of theimplant 154 are laterally separated such that they clear the engagementfeatures 158 on the arms 148 of the driver assembly 142. As shown inFIG. 26, when the implant distractor 150 has been fully advanced and theimplant 154 is in place, the driver assembly 142 may be slidably removedfrom the delivery device 104 leaving behind the implant distractor 150and the implant 154.

FIG. 27 shows yet another device, the device being adapted for placingbone paste over the implant 154 in the joint. An injector 202 is shownand includes a syringe type cannula 204 with a closed distal end 206 andtwo exit doors 208 positioned on opposite sides of the distal end 206 ofthe cannula 204. The cannula 204 includes a plunger 210 with a seal andfurther includes a stopping disc 212 at its proximal end, the plunger210 penetrating the stopping disc 212 and having a handle 214. Thecannula 204 may have an outer radius substantially equal to that of theinner radius of the delivery device 104 to allow for slidable engagementof the two devices. The disc 212 at the proximal end is generally flatand is adapted to engage the receiving assembly 110 of the deliverydevice 104 and provide a stop point for the injector 202 when insertedinto the delivery device 104. As shown, the cannula 204 may contain abone paste material in a liquid form.

As shown in FIG. 28, the injector 202 may be inserted into the deliverydevice 104 and slidably advanced such that the distal end 206 is nearthe implantation site and the disc 212 abuts the annular ring 118 of thereceiving assembly 110 of the delivery device 104. The injector 202 maybe rotatably positioned such that the doors 208 are positioned to openperpendicular to a line connecting the distal ends of the forks 112. Thedisc 212 may include tabs 216 for such positioning relative to theannular ring 118 on the receiving assembly 110. Once in position, theplunger 210 may be actuated to compress the bone paste material creatingan internal pressure which forces the exit doors 208 open allowing thebone paste to escape and flow over the implantation site.

The above description has included some references to use to allow for abetter understanding of the structure. Below is a more detaileddiscussion of that use including the devices and techniques fordistracting and retaining a facet joint in a distracted and forwardlytranslated condition. The implantation procedure may be performed underconscious sedation in order to obtain intra-operative patient symptomfeedback.

Initially an incision may be made in the patients back. Tools known inthe art may be used to create this incision and to open an access paththrough the tissues of the back to access the spine. Once an access pathis created, the chisel 108 described above may be inserted into thedelivery device 104 and the two of them may be inserted through theincision and the distal tip 130 may be positioned adjacent the targetfacet joint. It is noted that visualization may be provided by firstinserting a scope down the delivery device 104 rather than the chisel108. Additionally, an incision in the facet joint capsule may be madeprior to beginning the procedure, and thus prior to insertion of thechisel 108. Once the distal tip of the delivery device 130 is properlypositioned adjacent the facet joint and any other preparation steps arecompleted, the chisel 108 may be inserted. Once the chisel 108 anddelivery device 104 are properly positioned, the head 132 of the chisel108 may be tapped with a driving device 140 such as a hammer or otherinstrument to advance the distal tip 130 of the chisel 108 and the forks112 of the delivery device 104 into the facet joint. Once the deliverydevice 104 is properly positioned, the chisel 108 may be removed. Atthis point, the implant 154 may be placed in the driver assembly 142 andthe implant 154 and driver assembly 142 may be slidably advanced throughthe delivery device 104. The forks 112 of the delivery device 104 may beholding the facet joint slightly distracted. As such, the implant 154,in its flat and parallel position, may slide relatively easily into thefacet joint. To the extent that it does not, the proximal end of thedriver assembly 142 may be tapped to properly advance and position theimplant 154. Once properly positioned, the distractor knob 144 on thedriver assembly may be rotated or otherwise actuated to activate theinternal actuator 152. The internal actuator 152 advances the implantdistractor 150 into the implant 154 and thus distracts the implant 154.It is noted here that the distraction of the implant 154 may cause theupper 168 and lower 170 member of the implant 154 to clear theengagement features 158 of the holder arms 148 thus allowing the driverassembly 142 to be freely removed from the delivery device 104 leavingthe implant 154 and the implant distractor 150 behind. The injector 202may then be advanced through the delivery device 104 and positioned toallow the doors 208 to open in a direction approximately perpendicularto the forks 112 of the delivery device 104. The handle 214 may bedepressed thus advancing the plunger 210 and ejecting the bone paste orother anchoring material. The injector 202 may then be removed. Thedelivery device 104 may also be removed and the incision closed.

Those skilled in the art will understand and appreciate that severalmodifications or variations from the above the identified embodimentsmay be made while still falling within the scope and spirit of thepresent disclosure. For example, several alternative actuationmechanisms at the proximal end of the tool for actuating the distractingelements of the tool may be available. Additionally, several alternativeimplants may be available. For example, as shown in FIGS. 29 and 30, animplant 218 similar to that previously described is shown and includes abody 220 and a screw 222. The body 220 includes an upper 224 and lower226 face joined together at a leading end 228 and separated from eachother at a trailing end 230.

As shown in FIG. 29, when the screw 222 is not received in the body 220,the upper 224 and lower 226 faces may reside against each other suchthat the body 220 is generally flat. As shown in FIG. 30, when the screw222 is received in the body 220, the upper 224 and lower 226 faces maybe separated from each other, the degree of separation increasing as thescrew 222 is increasingly received in the body 220. As the upper 224 andlower 226 faces are separated from each other, the body 220 takes onmore of a wedge shape, with the leading end 228 being the narrow end ofthe wedge and the trailing end 230 being the wide end. The faces mayinclude teeth 232 and the trailing end 230 of the upper face 224 may beformed to project towards the leading end, both of these featuresassisting in the implant 218 anchoring to the bone facet surfaces. Holes234 may exist in the faces 224, 226 such that when the screw 222 isreceived in the body 220, the thread edges of the screw 222 may projectthrough the holes 234 to bite into the facet surfaces. The wedge shapeof the implant 218 may facilitate anchoring the implant 218 within thefacet joint and may also facilitate distraction, translation, orsubluxation of the facet surfaces relative to each other.

As can be understood from FIG. 29, the collapsed and flattened body 220may be placed between the opposing surfaces of the facet joint. Theposterior or trailing end 230 of the body 220 is configured to becapable of receiving a screw, bolt, or some other inserted component222. As indicated in FIG. 30, upon insertion of the screw, bolt, etc.222, the body 220 begins to expand. This expansion and separation isenabled by a hinge 236 at the anterior or leading end 228 of the body220. As the body 220 expands, sharp directional teeth, cleats, or keels232 on the opposing (superior & inferior) surfaces or faces 224, 226 ofthe body 220 may become anchored in the cortical bone of the opposingfacet surfaces. These teeth, cleats, or keels 232 may engage the facetsurfaces and provide acute fixation of the body 220 within the facetjoint. The teeth, cleats, or keels 232 may be included on only onesurface 224, 226 as opposed to both surfaces 224, 226 so as to allow fora movement of the joint after placement of the implant 218.

The distraction and separation of the facet joint via the expandedimplant (see FIG. 30) may increase foraminal area and reduce thesymptoms associated with nerve root compression.

Another implant embodiment is depicted in FIGS. 31 and 32, wherein ascrew 238 also acts to spread apart the faces 240, 242 of the body 244of the implant 236. In this embodiment, the implant 236 may have anupper 240 and a lower 242 member positioned adjacent to each other. Theupper 240 and lower 242 member may be substantially rectangular with adistal edge a proximal edge and parallel lateral edges. The distal edgemay be slightly radiused. The upper 240 and lower 242 members may beconnected along their distal edge by a connection member 246 in the formof a triangularly bent plate or other connection. The connection membermay include a penetration 248 adapted to receive an implant distractor238. As with the previous embodiments, the implant 236 may include teeth250 on the outer surface of the upper member 240 or the lower member 242or both as shown. In one embodiment, the implant 236 may be formed froma single plate and folded to create the shape shown. In use, the implant236 may be positioned in a facet joint and the implant distractor 238may be advanced thereby separating the upper 240 and lower 242 memberand distracting the joint. Similar to that discussed above with respectto FIGS. 29 and 30, such an embodiment as depicted in FIGS. 31 and 32may have holes (not shown in FIGS. 31 and 32) in the body surfaces 240,242 so as to allow the threads of the implant distractor 238 to extendthrough the surfaces of the body 244 to bite into the facet surfaces.

FIGS. 33 and 34 depict isometric views of another implant 248 withV-shaped members 250 residing on a threaded bolt 252 between an anteriorthreaded block 254 and a posterior non-threaded block 256. The V-shapedmembers 250 may slidably engage the bolt 252. As shown in FIG. 33, theV-shaped members 250 are in a non-expanded state and are spaced apartfrom each other along the length of the bolt 252. The implant 248 may beinserted into the facet joint in the non-expanded state depicted in FIG.33. As can be understood from FIG. 34, the bolt 252 may be rotated tocause the anterior threaded block 254 to travel along the bolt 252towards the posterior non-threaded block 256. It is noted that in use,the rotation of the blocks 254, 256 may be prevented by their positionwithin a facet joint, thus causing the anterior threaded block 245 totravel rather than rotate when the bolt 252 is rotated. The posteriornon-threaded block 256 may be in abutting position against the head 258of the bolt 252 thereby preventing it from moving away from the anteriorthread block 254. Thus, as the anterior threaded block 254 advancestoward the posterior non-threaded block 256, the V-shaped members 250are squeezed together. As the V-shaped members 250 are increasinglysqueezed together between the blocks 254, 256, the V-shaped members 250are increasingly expanded outward, thereby biting into the facet jointsurfaces to anchor the implant 248 in the facet joint and distract,translate and/or subluxate the facet surfaces relative to each other.

FIGS. 35-36 and 37A-D, depict isometric views of another implant 260with planar plates or leaves 262 residing on a threaded bolt 264 andparallel shafts 266 between an anterior threaded block 268 and aposterior non-threaded block 270. As shown in FIG. 35, the planar plates262 are in a skewed non-expanded state and are spaced apart from eachother along the length of the bolt 264 such that may lie generally flator, more specifically, at approximately 45 degrees on the bolt 264 andshafts 266. The plates 262 may include a slotted hole for receiving thebolt 264, which allows for the position described. The implant 260 maybe inserted into the facet joint in the non-expanded state depicted inFIG. 35. As can be understood, the bolt 264 may then be rotated to causethe anterior threaded block 268 to travel along the bolt 264 towards theposterior non-threaded block 270, thereby causing the planar plates 262to squeeze together. As the planar plates 262 are increasingly squeezedtogether between the blocks 268, 270, the planar plates 262 areincreasingly expanded outward or, more specifically, are caused to begenerally perpendicular to the bolt 264 and shafts 266. As a result, theplanar plates 262 bite into the facet joint surfaces to anchor theimplant 260 in the facet joint and distract, translate and/or subluxatethe facet surfaces relative to each other.

FIGS. 37A-D show an embodiment, which combines features of theembodiment shown in FIGS. 33 and 34 with features of the embodimentshown in FIGS. 35 and 36.

FIGS. 38A-C shows another embodiment of an implant 272. The implant 272may include two stacked structures 274 that interface along a plane 276.Each structure 274 may include opposing ratchet teeth 278 along theplane. The position and orientation of the ratchet teeth 278 may be suchthat relative translation between the two structures 274 is allowed whena force is applied to each structure 274 in opposing directions. Thatis, once the implant 272 is properly positioned within the facet, adevice may be use to apply a force to the superior structure 274 whichcauses forward translation of that structure 274 relative to theinferior structure 274. The ratchet teeth 278 on the superior structure274 may slide up the slope of the teeth 278 on the inferior structure274 until opposing apexes of teeth 278 pass by each other causing thetwo structures 274 to nest in a new relative position, the displacementbeing equal to the length of the teeth 278. Each structure 274, or onlyone of the structures 274, may increase in thickness along its length,such that continual relative ratcheted displacement creates a greateroverall thickness. The increasing thickness of the implant structures274 may cause distraction and forward translation in the facet joint.The opposing facet surfaces may be separated and the superior vertebramay be pushed anterior relative to the inferior vertebra. In addition,anchoring teeth 280 may be provided on the outer surface of bothstructures 274 of the implant 272 to provide acute fixation to thearticular surfaces. The implant 272 may be configured in a number ofdifferent shapes including, but not limited to, a wedge, a double wedge,a rectangular box, and “v”shaped.

FIGS. 39A-D show another embodiment of an implant 282. In thisembodiment, a screw like implant 282 may be inserted between the facet.The insertion of this screw may serve to distract the joint surfacesresulting in a decompression of the nerve root. Additionally, thethreads 284 of the screw may include V-shaped notches 286 in the threads284 spaced throughout the length of the screw creating serrated teeth.As the screw implant 282 is threaded progressively further anterior, theserrated teeth may cut/bore into the cortical bone of the opposing facetsurfaces. The defect in the bone these serrations produce may preventthe implant 282 from backing out posteriorly or migrating medial/lateralbecause the threads 284 are configured with the serrated teeth to allowthe implant 282 to catch or “bite” in the bone if any posterior withdrawor backing out occurs. Additionally or alternatively, as shown in FIGS.40A-C, the screw threads 284 may include a leaf spring 288 to maintainfriction of the threads 284 against the newly cut threads in the bonethereby preventing the screw from backing out.

FIGS. 41A-D show another embodiment similar to the one shown in FIGS.39A-D. That is, in this embodiment, the implant 290 may take the form ofa screw, but the threads 292 of the screw may have a T-shaped profile asshown in FIG. 41D. In addition, the flat surface of the T-shaped profilemay define a diameter at any given point along the length of the screw.In one embodiment, the diameter may increase over the length of thescrew and not be limited to just the tip like a traditional screw. Assuch, when the implant 290 is placed, the more it is advanced into thefacet joint, the more separation it creates.

FIGS. 42A-F show another embodiment of an implant 294. In thisembodiment, the implant 294 may again take the form of screw. The screwmay have a washer or extra broad head 296 with sharp protrusions 298 onthe distal surface of the head 296 that engage the superior and inferiorlateral mass surfaces as the screw is inserted into the facet joint. Theengagement of the sharp protrusions 298 may occur as a result of boththe longitudinal translation of the screw together with the rotationalmotion causing the sharp protrusions 298 to cut into the lateral masssurface as the screw is advanced and rotated. As the washer 296 rotates,the sharp protrusions 298 roughen the lateral masses and create afracture environment. This fracture environment causes osteoblasticactivity that will lead to bone production and assist in fusion of thejoint at the lateral mass. Moreover, the moat created by the rotatingand cutting protrusions 298 may begin to lock the facet surfacestogether.

In the present embodiment, the protrusions 298 may be tab like and cutrelatively deeply into the lateral mass. In addition as shown in FIGS.42D-F, the tabs may position themselves as shown where the superior tabis flared to engage the lateral mass and the inferior tab is wedged intothe joint. In this configuration, the tabs may act to further distractthe joint beyond that provided by the diameter of the screw portion ofthe implant. In other embodiments, as shown in FIGS. 43A-C, the sharpprotrusions 300 may be sharp prongs or spurs adapted to roughen thesurface.

FIGS. 44A-D show another embodiment of an implant 302. In thisembodiment, a facet distraction implant 302 has a floating collar 304for use with a screw type implant. As shown, the collar 304 may bepositioned to pivot about the head 306 of the screw due to the sphericalshaped head 306 on the screw in a ball and socket fashion. The floatingcollar 304 allows the screw implant to accommodate irregular, non-planarsurfaces of the lateral mass and may aid in the prevention of reversethreading of the implant 302 once the screw has been advanced to theproper position within the facet. As shown, the screw may be implantedto provide distraction and forward translation of the joint. Thefloating collar 304 may include teeth or spikes 308 thatroughen/decorticate the cortical bone of the superior and inferiorlateral masses resulting in the creation of a fracture environment. Thismay improve the chance of posterior lateral mass facet fusion.

FIGS. 45A-D show yet another embodiment of a decorticating screw typeimplant 310.

FIGS. 46A-D show another embodiment of an implant 312. In thisembodiment, a structural implant 312 is inserted between the opposingsurfaces of a facet joint. This implant 312 may be in the form of ascrew as described above or may be a different implant requiring atorque or other force to be applied to anchor the implant 312 in thefacet joint. As shown, when the implant 312 is inserted increasinglymore anterior within the facet, a torque limiting mechanism 314 withinthe device may measure the force or torque applied to the system. Once apredetermined value of torque or force is achieved, the distal end ofthe system may detach causing the implant 312 to become a permanentdistraction implant.

In the case of a screw implant, the torque limiting mechanism 314 may bea necked down portion of the device creating a calibrated weakenedportion intended to fail when a specified torque is exceeded.

In this embodiment, the implant 312 may also include a number of anitmigration features to prevent backout. These features may includedirectional teeth, roughened surfaces, keels, spikes, or other featuresknown in the art. As with other implants, the geometry of the implantmay cause distraction of the joint and lead to a more pronounced forwardtranslation of the joint as the opposing facet surfaces separate.

FIGS. 47A-B show another embodiment of an implant 316. In thisembodiment, again a screw shaped implant 316 may be inserted into thefacet to distract the facet surfaces and increase foraminal heightresulting in a decompression of a symptomatic nerve root. In thisembodiment, however, the implant may include two main components. First,the implant 316 may include a relatively stiff but maleable cone-shapedscrew structure 318 with aggressive threads for biting into the opposingsurfaces of the facet joint. These threads may have a number ofvariations for preventing movement of the implant after it is implanted.Second, the implant may include an inner core support member 320. Thecore support member 320 may be in place when the implant 316 is placedto assist in maintaining the shape of the screw structure 318. Afterplacement, the core support member 320 may be removed. The maleabilityof the screw structure 318 may allow it to collapse slightly once theimplant 316 is properly positioned and inserted. The collapsing of thescrew structure 318 would change the alignment of the threads andprevent reverse threading that could lead to posterior migration.

Yet another embodiment is show in FIGS. 48A-C. In this embodiment, asuperior 324 and an inferior 326 screw may be used to create an implant322. The two screws 324, 326 may have communicative threaded serrationsthat work in opposition to one another. As such, when the inferior screw326 is rotated, the threads may interact with the superior screw 324causing it to rotate in the opposite direction. Moreover, the threads onthe inferior screw 326 and superior screw 324 are such that oppositedirection rotation draws both screws 324, 326 in to the facet joint. Asthe screws 324, 326 enter the joint, the facet surfaces are distractedapart from one another and the threads of the screw bite into the facetsurfaces. The opposing rotation of the two screws 324, 326 may alsoassist in preventing back out of the implant or reversethreading/unscrewing. It is noted that several configurations may beused to create the opposite rotation of the screws. In one embodiment, ahousing may be placed over each screw allowing the screws to freelyrotate relative to the housing, but securing the screws adjacent to oneanother. In this embodiment, the opposite rotation may occur due to thethreads engaging with one another as described above or the screw headsmay have gear teeth for engaging one another and causing oppositerotation. In another embodiment, the screws may have gears on thempositioned within the housing to engage one another and cause oppositedirection rotation.

FIGS. 49A-C show yet another embodiment of an implant 328. In thisembodiment, a translating system including a vertical plate 330 and abumper 332 may be included. The superior aspect 334 of the bumper 332may have a rounded concave surface for opposing the lateral mass of asuperior vertebra. The translating system may be secured by anchoring ascrew 336 to the lateral mass of an inferior vertebrae. The screw 336may act as the foundation for a bumper system intended to push asuperior vertebra forward (anterior) creating translation of thesuperior vertebra relative the the inferior vertebra. This forwardtranslation may create an increase in foraminal area and results in adecompression of the nerve root. The implant 328 may be configured tomaintain permanent forward translation in order to prevent foraminalnarrowing and nerve root compression. In addition, the implant 328 mayprovide rigid resistance when the superior vertebra exerts posteriortranslation vectors because it is anchored by the inferior lateral massscrew. The prevention of this posterior translation may keep the segmentin a state of forward translation and preserve the associated increasein foraminal area.

FIGS. 50A-B show another embodiment of an implant 338. In thisembodiment, a wedge shaped or triangular implant 338 may be insertedbetween the face surfaces. The angled/pointed portion 340 with two acuteline segments may allow the implant 338 to enter into the flat facetjoint when sufficient force is applied. As the implant 338 is insertedprogressivley more anterior, the distraction of the opposing facetsurfaces may increase. This separation results in an increase offoraminal height and decompresses the symptomatic nerve root.

The surfaces of this implant 338 may include teeth, spikes, cleats,surface roughening, and/or keels 342 to help prevent migration orbackout. In another configuration of this embodiment, as shown in FIGS.51A-B, the wedge shaped or triangular implant 338 may be anchored inposition by one or two (one shown in FIG.) lateral mass screws/nails 344that would connect the superior & inferior aspects of the implant 338 tothe corresponding superior & inferior lateral masses of the affectedsegment.

FIGS. 52A-C show another embodiment of an implant 346. In thisembodiment, a distraction/translation system may include an anteriorhook 348 and a posterior hook 350 joined by a threaded bolt 352. Theanterior hook 348 may be placed over the anterior aspect of the inferiorfacet and the posterior hook 350 may be positioned posterior to thesuperior facet. The anterior hook 348 may have a C-shaped profile with alip for engaging the anterior aspect of the inferior facet. Theposterior hook 350 may have a S-shaped profile with a lip for engagingthe posterior aspect of the superior facet. The threaded bolt 352 may bepositioned through the facet joint and may threadably engage a posteriorleg 354 of the anterior hook 348 and an anterior leg 356 of theposterior hook 350 as shown. As the bolt 352 is tightened and the hooks348, 350 are drawn together, they create anterior translation of thesuperior vertebra relative to the inferior vertebra. This translationmay result in increased foraminal area and nerve root decompression. Thetranslation is maintained through the permanent placement of the hooksand bolt.

FIGS. 53A-C show another embodiment of an implant 358. In thisembodiment, an insert 360 may be placed in the facet joint between twoopposing facet surfaces. The geometry of the implant 358 could take anumber of shapes including, but not limited to, rectangular, concical,triangular, or trapezoidal shape. Once the implant 358 is properlypositioned, it may then be rotated some degree of rotation. Thisrotation may result in an increased height of the implant and causefacet surface separation and thus increased foraminal area anddecompression of the symptomatic nerve root. In another configuration asshown in FIG. 53C, the rotated implant 358 may have outer tabs 362 thatare capable of receiving a bone screw, nail, or pin that can be anchoredin the superior and inferior lateral masses. These tabs 362 and anchorsmay assist in the prevention of implant migration leading to a reductionin the foraminal area.

FIGS. 54A-C show another embodiment of an implant 364. In thisembodiment, an implant 364 may take the form of a collapsible diamondshape 366 with an adjustment bolt 368 abutting a first corner 371 andthreaded through an opposing corner 370 of the shape. The other corners372 may include pads 374 for positioning against opposing articularfaces of a facet joint. The implant 364 may be placed into the facetjoint in a collapsed position and the adjustment bolt 368 may then beactuated to draw the opposing corners 371, 372 of the shape togetherthereby expanding the shape and pressing the pads 374 against thearticular faces. As the shape expands, additional facet distraction isachieved resulting in an increased foraminal opening. This implant 364may be provided in a number of geometries or materials to providedirectional distraction where, for example, more distraction occurs nearthe posterior edge of the facet relative to the anterior edge of thefacet. Additionally, the surface of the pad 374 may include teeth orkeels to enable bone purchase in the facet.

FIGS. 55A-C show another embodiment of an implant 376. In thisembodiment, the implant 376 may take the form of an expandable hingedstructure with an upper member 378 and a lower member 379 connected attheir distal ends 380 by a hinge 382. The implant 376 may be placedbetween the facet surfaces in a collapsed state. The posterior aspect ofthe implant 376 may include a receiving slot that is able to receive ascrew, bolt, or other activiation system. Engaging this slot with anactivator would cause the implant 376 to expand on its hinge 382creating distraction and translation of the joint. For example, theactivator may be a wedge, a turnable flat tool, a tapered screw, or anyother device that may be inserted into the receiving slot to forciblyexpand the upper 378 and lower 379 members. As shown, the hinge 382 mayalso include a brace member 384 for maintaining the posterior halves ofthe hinge in a separated position. The brace member 384 may be springloaded or otherwise engaged with the hinge halves 378, 379 such thatwhen expanded the brace 384 moves into position to support the openposition of the hinge 382. In some embodiments, the upper 378 and lower379 member of the implant 376 may have teeth, cleats, or keels 386 toengage the cortical bone of the opposing facet surfaces. Thesemechanisms would provide fixation of the implant 376 to the joint.

FIGS. 56A-C include another embodiment of an implant 388. In thisembodiment, a collapsed and flattened structure 390 may be placedbetween the opposing surfaces of the facet joint. The posterior aspect392 of the structure 390 may be configured to be capable of receiving ascrew, bolt, or some other inserted component 394. Upon insertion of thescrew, bolt, etc. 394, the structure may begin to expand. This expansionand separation may be enabled by a hinge 396 at the anterior aspects ofthe structure 390. As the structure 390 expands, sharp directionalteeth, cleats, or keels 398 on the opposing (superior & inferior)surfaces of the structure may become anchored in the cortical bone ofthe opposing facet surfaces. These teeth, cleats, or keels 398 mayengage the face surfaces and provide acute fixation of the structurewithin the facet joint. Together with the these teeth, cleats, or keels398, or as an alternative to them, as shown, the proximal end of theimplant 388 may also include flanges 400 that overlap the lateral massof the facet joint. These flanges 400 may include holes 402 foranchoring the implant 388 to the superior and inferior facet masses, orto only one of the masses. In a related embodiment, the superior andinferior surfaces may have open ports 404 that enable the screw threadsto exit the structure and gain purchase in the opposing facet surfaces.The distraction and separation of the joint may increase foraminal areaand reduce the symptoms associated with nerve root compression.

FIGS. 57A-C show yet another embodiment of an implant 406. In thisembodiment, the implant 406 may resemble a screw and wall anchor. Thewall anchor portion 408 may be generally cylindrically shaped andinclude two half sections 410 separated by a slot or it may include amultitude of longitudinally extending sections 410. These sections 410may be connected together at the tip 412 as shown or they may beconnected together at the proximal end 414 of the implant 406 and at thetip 412 and may include several connections along the length of theimplant 406. The implant 406 may have a sharp, triangular or conical tip412 that allows for access into the flattened facet joint. Once theimplant 406 is inserted into the facet surface, a screw, bolt, or otherinsertion component 416 may be inserted into the implant 406. As thiscomponent 416 is advanced the sections 410 may expand creatingadditional separation of the joint and allowing for measured distractionof the space. The sections 410 of the wall anchor portion 408 mayinclude sharp directional teeth, cleats, or keels 418 that engage thecortical bone of the opposing facet surfaces.

FIGS. 58A-B show yet another embodiment of an implant 420. In thisembodiment, a tool 422 may be used to apply a force to the superiorvertebra of a motion segment. This forward translation would result inan increase in foraminal area and reduced nerve root decompression.Following the forward translation of the motion segment, an angled screw424 would be placed through the superior facet surface, facet capsule,and inferior facet surface. This screw 424 would provide temporaryimmobilization of the joint which leads to fusion.

FIGS. 59A-B show yet another embodiment of an implant 426. In thisembodiment, a collapsed, triangular shaped implant is inserted into thefacet. The implant 426 may include a central shaft 428 and two or morespringing leaves 430. The leaves 430 may be connected to the distal endof the shaft 428 and may extend proximally along the shaft 428. Theleaves 430 may be connected at the distal end so as to be biased in adirection to form an arrow shape. The leaves 430 may be held in thecompressed state by an insertion & delivery tool 432. The deliverytool's compression of the implant 426 prevents the superior and inferiorsurfaces of the implant 426 from springing open to a distractedposition. Once the compressed implant 426 is positioned correctly, thedelivery tool 432 may be removed. Removing the tools causes the leaves430 to open/expand causing distraction and separation of the facet jointthus resulting in increased foraminal area and reduced nerve rootcompression.

FIGS. 60A-B show yet another embodiment of an implant 434. This concepthas at least three embodiments. The first embodiment consists of adirection facet joint screw 436 that is advanced through an inferiorfacet until it makes contact with the opposing superior facet. Once thescrew 436 makes contact with superior facet surface, the energy appliedto advance the screw 436 results in distraction and separation of thejoint due to bearing of the screw tip 438 on the underside of thesuperior articular surface. In one variation of this embodiment, thehole for the screw in the inferior facet may be pre-drilled. When thescrew is installed and encounters the superior facet, the screw may biteinto the superior facet as it forces the fact upward and distracts thejoint. Alternatively, in this embodiment, the screw may have a blunt tip438 to distract the joint without biting into the superior facet.

In the second embodiment, as shown, a directional facet screw 436 may beadvanced through the inferior facet surface until it engages with afacet spacer/plate 440 that is inserted in between the facet surfaceswithin the facet capsule. As the screw 436 makes contact with the facetspacer/plate 440, the flat surface of the spacer/plate 440 may push upagainst the opposing superior facet surface causes distraction andforward translation. This separation of the facet surfaces results inincreased foraminal area and reduced nerve root compression.

In a third embodiment, the spacer/plate 440 may have a shape to allowthe screw 436 to pass through a first end and the other end to be placedin the facet joint. In this embodiment, the C-shaped spacer 440 may bepositioned in the joint, thereby slightly distracting the joint. Thescrew may then penetrate a first end of the spacer 440 thereby anchoringthe spacer 440 in the joint. The screw may then be advanced through theinferior facet surface until it engages with the spacer/plate 440. Asthe screw 436 makes contact with the facet spacer/plate 440, the flatsurface of the spacer/plate 440 may push up against the opposingsuperior facet surface causes distraction and forward translation. Insome embodiments, the screw may penetrate the spacer and aid in fixingthe joint.

FIGS. 61A-C show yet another embodiment of an implant 442. In thisembodiment, bracket type structures 444 may be attached to the superiorand inferior lateral masses. The bracket type structures 444 may enablethe attachment of a single bolt 446. The bolt 446 may be configured tocreate a distraction energy. That is, it may be connected to theinferior bracket 444 to allow rotation but not relative translation. Incontrast, the bolt may threadably engage the superior bracket 444. Assuch, when the bolt 446 is “unscrewed” it may function to push theinferior and superior brackets 444 apart. This distraction may result inincreased foraminal area and reduction in nerve root compression.

FIGS. 62A-C show yet another embodiment of an implant 448. In thisembodiment, bracket type structures 450 may each have a leg 452 forpositioning within a facet joint and another leg 454 for receiving abolt 456. As with the bracket above, the bolt 456 may be configured tocreate distraction energy. That is, it may be connected to one of thesuperior or inferior bracket 450 so as to allow rotation but notrelative translation. The other bracket 450 may threadably engage thebolt 456. As such, when the bolt 456 is “unscrewed” it may function topush the brackets apart resulting in and increased foraminal area.

FIGS. 63A-C show yet another embodiment of an implant 458. In thisembodiment, a triangular shaped implant 458 including a bent plate and afiller wedge may be inserted in the facet joint. As the triangularimplant 458 is inserted progressively more anterior, the joint may bedistracted to an optimal level. Once the desired distraction isachieved, an anchoring screw 460 may be inserted through the implant 458and into the inferior lateral mass. The superior aspect of the implant458 may include a metal flap 462 with teeth, spikes, or cleats 464. Thismaleable flap 462 may be contoured to the superior lateral mass andanchored using its teeth, spikes, or cleats 464. The metal flap 462 andinferior screw 460 may provide permanent fixation of the triangularimplant 458 to enable permanent distraction of the facet andimmobilization of the joint facilitating permanent fusion of the joint.

FIGS. 64A-C show yet another embodiment of an implant 466. In thisembodiment, a distraction system consists of a central anchoring plug468, an initiating plate 470, and two external plates 472. The twoexternal (superior and inferior) plates 472 may be attached to thelateral masses of a motion segment and may be anchored using screws. Theinitiating plate 470 may then be inserted in the gap 471 between theexternal plates 472 to initiate opening of the plates 472 and the jointand allow for further insertion of the anchoring plug 468. Following theinsertion of this initiating plate 470 and turning or manipulating theplate 470 to open the external plates 472, the central anchoring plug468 may then be advanced into the gap 471 between the external plates472 causing expansion of the plates and distraction and separation ofthe joint.

FIGS. 65A-C show yet another embodiment of an implant 474. In thisembodiment, nitinol hooks 476 may be configured to have a memory. Thehooks 476 may be flattened and inserted through a delivery system 478.The delivery system 478 may be placed in a facet joint. Once insertedwithin the facet, the nitinol hooks 476 may be activated viatemperature, force, or other activation means causing them to assumetheir original (pre-flattened) shape and hook into the opposing facetsurfaces. As the hooks 476 engage the cortical bone of the facetsurfaces, they distract the joint. This separation results in increasedforaminal area and reduced nerve root compression.

FIGS. 66A-C show yet another embodiment of an implant 480. In thisembodiment, a hollow screw sleeve 482 may be placed within the facetjoint. A wedge 484 may then be placed within the hollow screw sleeve 482causing it to expand and distract the joint. Additionally, the screwsleeve 482 may include sharp barbs 486 having a retracted position and aejected position. As the wedge 484 is inserted, the wedge 484 displacesthe sharp barbs 486 causing them to be ejected through the screw sleeve482 and engage the facet surfaces. These barbs 486 may provide acutefixation of the implant 480 to the joint and prevent migration of theimplant 480. The distraction and separation of the joint result inincreased foraminal area and reduced nerve root compression.

FIGS. 67A-C show yet another embodiment of an implant 488. In thisembodiment, a panel anchor implant 488 may be placed within the facetjoint. The implant 488 may include a bolt 490 and collapsible nut 492that is rotationally free from the bolt 490 near the head of the bolt490 and threadably engaged with the bolt 490 near the end opposite thehead. As such, when the bolt 490 is advanced, the distal end of the nut492 is squeezed toward the proximal end of the nut 492 and the nut 492may collapse with an accordion effect. As shown, the compression of thenut 492 results in a taller structure that applies a distraction forceto the opposing facet surfaces. This distraction leads to increasedforaminal area and reduced nerve root compression.

In similar fashion, the embodiment shown in FIGS. 68A-C may collapsecausing distraction of the joint. In lieu of the nut 492 shown in FIGS.67A-C, this embodiment, shows a flat plate 494 that collapses into anaccordion shape.

FIGS. 69A-C show yet another embodiment of an implant 496. In thisembodiment, an implant 496 is placed within the facet joint. The implantcould have a number of shapes and sizes but, in this embodiment, has atension wire 498 that surrounds the implant 496 and is pulled taughtduring implantation. Once the implant 496 is properly positioned, thewire's tension is released. The release of this tension causes the wire498 to return to a preset expanded shape and height that causes theimplant 496 to expand. The expansion of the implant 496 as the wirereturns to its preset, and larger profile, shape causes separation ofthe facet joint. This distraction results in increased foraminal areaand reduced nerve root compression.

Similarly, as shown in FIGS. 70A-C, an implant 500 with an outer housing502 and an internal spring 504 may be positioned in the facet joint withthe wire spring 504 in a tensioned or elongated position. Once properlypositioned, the tension on the spring 504 may be released thuscollapsing the spring 504 and expanding the associated housing 502 ofthe implant 500.

FIGS. 71A-C show yet another embodiment of an implant 506. In thisembodiment screw type implant 506 may be provided and may also includean arm type locking mechanism 508. The locking mechanism 508 may extendfrom all sides of the head of the screw as shown and may be biased in adistal direction. As the screw advances, the locking mechanism 508 mayanchor in the lateral mass of a vertebra. The biased position of the arm508 pressing against the lateral mass may provide a force biasing theimplant 506 against the advancing direction. However, this may causeconstant friction between any newly cut threads in the surfaces of thefacet joint thereby preventing unscrewing or back out of the implant. Inaddition, teeth 509 may be included on the arms 508 and may bite intothe lateral mass further preventing backing out of the implant.

FIGS. 72A-C show yet another embodiment of an implant 510. In thisembodiment, two wedge shape opposing structures 512 are shown separatedby a sloping plane 514. The structures 512 may have a predeterminedrelative position, or a series of predetermined relative positions,where a bolt or screw 516 may be advanced at an angle as shown throughone of the structures 512 and into a predrilled hole of the other 512 tomaintain their relative position. Alternatively, the relative positionsmay not predetermined and a self-drilling screw 516 may be used. Ineither case, the implant 510 may be positioned in the facet joint inminimal profile position and then the two structures 512 may be slidrelative to each other along the sloping plane 514 to expand the implant510 and thus the facet joint. Once the desired position is achieved, thebolt, pin, screw, or other fastener 516 may be inserted to maintain therelative position of the structures 512.

FIGS. 73A-C show yet another embodiment of an implant 518. In thisembodiment, an implant 518 is configured to be inserted in a collapsedstate. In its non collapsed state, it has a vertical cylindrical profilewith side cutouts 520. When the implant is compressed, the side cutouts520 allow the wall panels 522 to bend out as the height of thecylindrical implant 518 is reduced. These wall panels 522 create ananchor shape that can engage bone structures. This implant 518 may beplaced within the facet join in its flattened, compressed profile. Onceit is positioned correctly, a distraction energy may be applied to theimplant 518 to cause it to expand or decompress. This decompressioncauses the implant 518 to attempt to return to its vertical cylindricalshape. The implant 518 may be made from a resilient elastic materialsuch as nitinol, stainless steel, or other known materials. As theimplant 518 becomes more cylindrical, it pushes against the opposingfacet surfaces. This force causes distraction of the facet joint andresults in increase foraminal area and reduced nerve root compression.

Similarly, as shown in FIGS. 74A-C, the implant 518 may be positioned onits side and the distraction energy may cause the implant 518 tocollapse from its cylindrical shape and expand laterally to distract thefacet joint.

FIGS. 75A-B show yet another embodiment of an implant 524. In thisembodiment, a delivery tool 526 is inserted within the facet joint. Thedistal tip 528 of the delivery tool 526 is shaped to distract the joint.Once the tool 526 is inserted into the facet joint and the desiredamount of distraction is achieved, the distal tip 528 (part that is inthe facet joint) may be detached from the delivery tool 526. In oneconfiguration of this embodiment, the detachable tip 528 would haveteeth, cleats, spikes, or keels 530 to prevent it from migrating withinthe joint once it is detached. In another configuration of thisembodiment, the implant 524 may be anchored in the facet joint byinserting a screw 532 through the superior facet, the implant, and theinferior facet. In both configurations, the detachable tip 526 (implant)may provide permanent distraction of the joint resulting in increasedforaminal area and reduced nerve root compression.

FIGS. 76A-C show yet another embodiment of an implant 534. In thisembodiment, the implant 534 may include a housing 536 with a centralgear 538 turnable by an allen type head 540 or other known attachmentfor turning, such as any known screwdriver heads. Adjacent the centralgear 538 on each side, the implant 534 may include two plates 542slidable in the housing 536 in a direction tangential to the gearsurface. The plates 542 may include teeth 544 engaging the central gear538 such that when the gear 538 turns, the plates 542 slide tangentiallyto the gear 538 and extend beyond an outer surface of the housing 536.As such, the implant 534 may be positioned in a facet joint as shown inFIG. 76A. Once positioned, the gear 538 may be turned thus extending theplates 542 in opposite directions and distracting the facet joint.

FIGS. 77A-C show another embodiment of an implant 546. In thisembodiment a triangular shaped implant 546 in the form of a bent plate548 may be wedged into the facet causing distraction and separation ofthe joint. On one side of the triangular distraction structure 548 is abracket 550 with a screw 552. The screw 552 may be inserted into thelateral mass to provide anchoring of the facet distraction implant 546.The other side of the triangular distraction structure 548 may includeteeth or other features 554 for biting into the associated lateral mass.The implant 546 would provide permanent distraction of the jointresulting in increase foraminal area and reduced nerve root compression.

FIGS. 78A-C show another embodiment of an implant 556. In thisembodiment, the implant 556 may have a tapered shape that is taller atthe posterior aspect relative to the anterior aspect. The implant couldbe tapped in, malleted in, screwed in with threads, or pushed in withhand pressure. Once the implant 556 is positioned correctly, the head558 of the implant 556 (posterior aspect) may be configured to havesharp teeth, spikes, or cleats that can be pushed into the cortical boneof the superior and inferior lateral masses of a motion segment. Theseflaps 558 could be hinged on the posterior aspect of the implant 556 toallow the flaps 558 to be pushed anterior enough to match the irregularcontours of the lateral mass. The implant 556 would provide permanentdistraction of the joint resulting in increase foraminal area andreduced nerve root compression.

FIGS. 79A-C show another embodiment of an implant 560. In thisembodiment, the implant 560 includes a single rotatable cone 562 with ashoulder shaped ledge 564 defining a cam surface 566, the distancebetween the ledge and the bottom of the implant defining a shoulderheight. The shoulder height may vary gradually from low to high and backto low along the circumferential perimeter of the cone 562. In use, theimplant 560 may be initially positioned such that the shoulder portionwith the low ledge height enters the facet joint. Once in position, theimplant 560 may be rotated to cause the higher ledge height to enter thejoint thereby distracting the posterior portion of the joint by causingthe superior articular face to ride upward along the cam surface 566.The implant 560 may then be secured with a screw 568 extending along thelongitudinal axis of the implant.

FIGS. 80A-D show yet another embodiment of an implant 570. In thisembodiment, an implant 570 may include a housing 572 with penetrations574 adapted for ejection of retracted spikes 576. Within the housing572, a wire 578 may be routed between the spikes 576 as shown in FIG.80D. The implant 570 may be inserted into the facet joint while the wire578 is relaxed and the spikes 576 are contained within the folds/curvesin the collapsed wire 578. Once the implant 570 is positioned correctly,the wire 578 may be pulled taught causing the spikes 576 to displaceoutwardly, extending out of the housing 572 and engaging the opposingfacet surfaces with a force. This force may create distraction andseparation of the joint, while the pointed tips of the spikes 576 wouldpenetrate the surface of the facet joint and provide acute fixationpreventing migration of the implant 570. The implant 570 would providepermanent distraction of the joint resulting in increase foraminal areaand reduced nerve root compression.

FIGS. 81A-C show yet another embodiment of an implant 580. In thisembodiment, an implant 580 may include a housing 582 with a cavity 584and penetrations 586 on lateral surfaces extending from the cavity 584through the wall of the housing 582, the penetrations 586 adapted forejection of retracted spikes 588. Within the housing 582, a threadedpiston 590 may be positioned at a distal end and may be adapted fordisplacement through the cavity 584 in the proximal direction. Thepiston 590 may have a torpedo shaped distal end 592 and may engage the abeveled inner surface 594 of the retracted spikes 588. The implant 580may be positioned within a facet joint and when properly positioned, thepiston 590 may be advanced via a turning tool, the torpedo shaped distalend 592 of the piston 590 thus engaging the beveled end 594 of thespikes 588 and advancing them laterally relative to the implant 580 outof the housing 582 with a force and into the face of the facets. Thisforce may create distraction and separation of the joint, while thepointed tips of the spikes 588 would penetrate the surface of the facetjoint and provide acute fixation preventing migration of the implant580.

FIGS. 82A-F show yet another embodiment of an implant 596. In thisembodiment, the implant 596 may include two parallel equal length sidebars 598 with pivoting struts 600 positioned on a pin 602 between thebars 598 at each end. The pivoting struts 600 may include texturedsurfaces 604 on each end and the struts 600 may be pinned to the sidebars 598 through one end. As shown in FIG. 82F, the struts 600 may havelength so as to allow them to be pivoted to lie parallel to one anotherin the plane of the side bars 598. In this position, the implant 596 maybe positioned in the facet joint as shown in FIG. 82A or anterior to thefacet joint as shown in FIG. 82D. Once properly positioned, the struts600 of the implant 596 may be rotated so as to be approximatelyperpendicular to parallel side bars 598 thus separating an inferiorvertebra from a inferior vertebra. It is noted that the generally stoutshape of the struts 600 with relatively broad textured ends 604 mayfacilitate stability preventing the implant 596 from racking back to theparallel condition.

Another variation of this embodiment is shown in FIGS. 83A-B, where aseries of varying height struts 600 are positioned along a shaft. Theentire implant may be placed within a facet joint on its side and then asingle ninety degree turn may position the implant and distract thejoint.

FIGS. 84A-B show yet another embodiment of an implant 606. In thisembodiment, two rotatable cams 608 may be positioned in a facet joint.It is noted that the cams may have a relatively low profile and theproportions in the FIGS. may be exaggerated for purposes of showing theconcept. Once placed in the joint, a distraction/rotation energy may beapplied to the cams causing them to rotate open to reveal two circularhalves of the cam implant. As one half of the implant rotatessuperiorly, it may push the superior vertebra upward creating anincrease in foraminal area and nerve root decompression.

In another embodiment, a kit is provided. As shown in FIG. 85 and 86,the kit may include a delivery device 610, a chisel 612, severalinternal and external decorticators 614, 616, 618, and a driver assembly620. As shown in FIGS. 87 and 88, the chisel head 622 and shaft 624 maybe provided in two pieces that may be combined with a press fit. Asshown in FIG. 89, the delivery device 610 may be provided in two piecescombinable with a press fit, the first piece being a tubular shaft andfork piece 626 and the second piece being a receiving assembly piece628. As show in FIGS. 90-93, the driver assembly 620 may be provided inseveral pieces including the internal actuator and the implantshaft/arms/handle portion. FIG. 90 shows the shaft/arms/handle portioncomprising two pieces, the first piece being a shaft with arms 630 andthe second piece being the handle 632. FIGS. 91 and 92 show the internalactuator including a tip 634, a shaft portion 636, an adapter 638, a pin640, and a distractor knob 642. In addition to the elements shown, oneor several implants may be provided as well as an injector as previouslydescribed. Several traditional instruments for use in accessing thesurgical site and closing the surgical site may also be provided.

Those of skill in the art will understand and appreciate that theimplant embodiments depicted herein may be made of several types ofbiocompatible materials including stainless steel, titanium, ceramics,nitinol, polymers, and other materials known in the art.

The above description has included some references to use to allow for abetter understanding of the structure. Below is a more detaileddiscussion of that use including the devices and techniques fordistracting and retaining a facet joint in a distracted and forwardlytranslated condition. The implantation procedure may be performed underconscious sedation in order to obtain intra-operative patient symptomfeedback. Before the facet joint can be distracted, however, the joint,which is difficult to access, must be accessed pursuant, for example, toa method and apparatus disclosed in U.S. provisional application Ser.No. 61/020,082, filed Jan. 9, 2008, which is commonly owned with thepresent application and hereby incorporated by reference. Pursuant tothe disclosure in that application, the access system may include one ormore cannulas made of steel, titanium, or plastic. The initial facetjoint access cannula may have a sharp spatula tip on the distal end. Thespatula tip may have a flat configuration to enable access into the flatfacet joint. Once the spatula tip achieves access into the flatlyoriented facet joint, subsequent stylets and working instruments may bepassed down this access channel to complete a distraction procedure.Alternatively the chisel and delivery device described above may be usedto access the joint. The distraction procedure may then begin.

The percutaneous distraction system may be introduced down the workingcannula of the above-identified access system using a handle or deliverytool that would allow the surgeon to generate distraction by applyingenergy to the handle for a distraction device at the proximal end of thedevice.

A distraction device may be inserted down the working cannula, forexample of the access system described previously, which is docked in afacet joint. Once the distal end of the distraction device is positionedat the anterior aspect of the joint, the surgeon applies energy to thedistraction device to create separation and distraction of the facetjoint. This separation occurs in both the vertical and horizontal planesof the joint resulting in vertical distraction and forward/anteriortranslation of the superior vertebrae relative to the inferiorvertebrae. The facet joint distraction and forward translation willcause an increase in foraminal area and may reduce nerve rootcompression and associated symptoms.

Although the present invention has been described with a certain degreeof particularity, it is understood the disclosure has been made by wayof example, and changes in detail or structure may be made withoutdeparting from the spirit of the invention as defined in the appendedclaims.

1. A spinal distraction implant comprising: an upper member and a lowermember, the upper member and lower member each being generallyrectangular and each having a distal edge, a proximal edge, and twoparallel lateral edges, the upper member and lower member positionedadjacent and substantially parallel to each other and having an innersurface and an outer surface, the distal edges of the upper member andlower member connected to each other by a U-shaped member positionedalong the distal edge of each of the upper member and lower member andthe proximal edges adapted to receive an implant distractor; and teethpositioned along the lateral edges of at least one of the upper memberor lower member and extending outwardly from the outer surface of the atleast one of the upper member or lower member.
 2. The implant of claim1, further comprising a receiving feature on a lateral edge of theimplant, the receiving feature adapted to receive an engagement featureof a driver assembly.
 3. The implant of claim 2, further comprising apair of distractor guide features, each positioned near the proximaledge of the upper member and lower member, the guide features adapted toguide an implant distractor between the upper member and lower member.4. The implant of claim 3, wherein the upper member and lower membereach include threaded slots for receiving threads of the implantdistractor.
 5. The implant of claim 4, wherein the distractor guidefeatures form a segment of a cone.
 6. The implant of claim 1, wherein afirst surface of at least a portion of the teeth is defined by a curvedportion of the inner surface of the upper member, wherein the curvedportion of the inner surface includes a first radiused curve that curvesaway from the lower member.
 7. The implant of claim 6, wherein a secondsurface of at least the portion of the teeth is defined by a curvedportion of the outer surface of the upper member, wherein the curvedportion of the outer member includes a second radiused curve offset fromthe first radiused curve.
 8. The implant of claim 7, wherein the teethhave a sloping distal face and a proximal face orthogonal to the uppersurface.
 9. The implant of claim 8, wherein the teeth are equallyspaced.
 10. The implant of claim 9, wherein the distal edges are coupledtogether via a weld.
 11. The implant of claim 1, wherein the U-shapedmember is a relatively thin rectangular piece of material formed intothe shape of a U.
 12. The implant of claim 11, wherein the U-shapedmember overlaps and is secured to the outer surface of the upper memberand lower member.
 13. The implant of claim 12, wherein the U-shapedmember abuts and is secured to the distal edges of the upper member andlower members.